Anesthesia Pharmacology:  Anxiolytics and Sedative-Hypnotics

• Pharmacological hypnosis: major drugs /drug classes

  • Introduction

    • If non-pharmacological treatment of insomnia (such as moderate exercise) is not effective, drugs may have to be used.

    • Untreated chronic insomnia may have many adverse effects including a four-fold increase in serious accidents.

    • In addition to use of pharmacological agents, management of insomnia should include:

      • (a) a search for an underlying cause

      • (b) elimination of "performance anxiety" related to falling asleep

      • (c) adjusting the patient's biological clock such that sleepiness corresponds to the time of attempted sleep, and

      • (d) suppression of the use of alcohol or over-the-counter sleep aids

  • Ethanol

    • Ethanol should not be used to manage insomnia because of numerous adverse effects.

      • For insomnia, despite reducing sleep latency, it may cause sleep fragmentation.

  • Barbiturates and non-barbiturates for hypnosis

    • Barbiturates and non-barbiturates such as meprobamate have been used in the past for pharmacological hypnosis.

    • However, these drugs should be avoided:

      •   Liabilities associated with barbiturate use include abuse potential, physical potentially life-threatening withdrawal reactions, dependence, and  life-threatening toxicity with overdosage.

  • Benzodiazepines

    • Hypnotics that act at benzodiazepine receptors and newer agents such as zolpidem (Ambien) are preferable to barbiturates because of: 

      • Greater therapeutic index

      • Less disruption of sleep patterns and

      • Less danger of overdosage toxicity

    • If the patient does not experience daytime anxiety, those benzodiazepines that exhibit short half-lives are preferable.

      • These short half-life agents with no active metabolites or only short-acting metabolites are preferable because they do not induce daytime sedation.

    • Triazolam (Halcion) is an example of a short-acting agent that has been used as a hypnotic. 

      • Short acting benzodiazepines may, however cause amnesia, early morning awakening, rebound daytime anxiety

    • Some patients who have insomnia also have daytime anxiety.

      • To manage those patients a longer-acting benzodiazepine may be appropriate.

        • Use of these agents may result in next-day cognitive impairment or delayed cognitive impairment as metabolites accumulate

        • Also, long-term benzodiazepine use may be a risk factor for long-term cognitive impairment.

Hobbs, W.R, Rall, T.W., and Verdoorn, T.A., Hypnotics and Sedatives: Ethanol In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics,(Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp. 385-386.

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